Horticulture container production needs a large volume of potting mixes and is typically short of supplies. Most container substrates are either bark-based or peat moss-based (Wright and Browder, 2005). Bark is relatively inexpensive and is the major substrate component in outdoor nursery production settings. Peat moss is more expensive and the major substrate component in greenhouse production settings. The supply of bark has decreased due to the house market and peat moss harvest has been targeted as the cause of destroying natural bog ecosystems (Robertson, 1993). Along with increased shipping cost, peat moss (shipping from Canada) is getting more and more expensive, which affects growers' profitability. The prices of two major container substrate components, peat moss and perlite, are relatively high in the range of $3.55-$6.35/ft3 (Premier Horticulture Inc.) and $10.95/ft3 (Ace Hardware), respectively. The wholesale price for Sunshine Mix #1, a commonly used greenhouse potting mix including both peat moss and perlite, is $4.57/ft3 from BWI in Jackson, Miss. It would benefit the green industry to have access to cheaper alternatives with similar physical and chemical properties.
Research activities currently ongoing are searching for alternative substrates including WholeTree, Woodgro, clean chip residual and switchgrass-based substrate (Fain et al., 2008; Wright et al., 2008; Boyer et al., 2008; Altland and Frantz, 2009). However, these alternative substrates have limitations including, but not limited to, additional input of fertilizers and/or other amendments, and/or limitations on the percentage that the alternative substrate can be incorporated in the container. In addition, another possible disadvantage of the wood-based or biomass-based alternative substrates is their potential shrinkage during plant production, especially for plants that require a long production cycle, due to decomposition of organic matters through the action of living organisms in these alternative materials.
Many research activities have also been focused on the use of industrial and agriculture waste, such as cotton gin compost (Papfotiou et al., 2007), kenaf and coconut coir pith (Goyne and Arnold, 1996), and biosolids and animal manure (Krucker et al., 2010). Although some of these alternative substrate components have had some positive aspects and could be amended to conventional substrate components, their widespread use in the horticulture industry is often limited by their limited supply of consistent quality product.
The search for alternative container substrate continues, especially for one that is relatively inexpensive, available in an abundant quantity and with little or no environmental impact, and that can be used as the sole component or major component of the container substrate. The present invention provides such a composition and method for making a substrate comprising biochar.
U.S. Patent Application Publ. No. US2011/0172092 (Lee, et al., application Ser. No. 12/686,831) involves a method for producing an oxygenated biochar material having a cation-exchanging property such that the biochar source acquires oxygen-containing cation-exchanging groups in an incomplete combustion process. The method of that application utilizes biochar in the ground as in-ground soil amendment. The present invention utilizes a novel biochar composition in containers as high value growing substrate (potting mixes). The application site of the biochar of the present invention uses a container or containers which could be composed of, but not limited to, a pot, box, bag, bucket, basket, tray, enclosed planting bed, and similar types of non-in-ground application sites. The present invention utilizes biochar as substrate and provides a novel biochar composition produced from the thermochemical conversion of biomass feedstock having novel particle size distribution of from about 0.5 mm to about 4 mm. The present invention can be utilized as a greenhouse substrate replacement, for example, and not an in-ground soil amendment as Lee, et al. provides, which is entirely different. Compositions of an in-ground soil amendment composition are completely different from the greenhouse substrate composition of the present invention, as well as the planting conditions that are very different. The biochar composition of the present invention can also replace container substrate components, for example, peat moss or pine bark. Current standard uses of biochar are for field uses to change in-ground soil quality. However, the present invention uses a novel biochar composition as a replacement of greenhouse substrate, for example, to more efficiently grow different types of plants.
A need exists in the field of plant substrate compositions for a novel biochar composition and method of producing such a biochar substrate and of growing plants more efficiently. The present invention provides such a composition and methods.